Limited cross-species transmission and absence of mutations associated with SARS-CoV-2 adaptation in cats: A case study of infection in a small household setting
Limited cross-species transmission and absence of mutations associated with SARS-CoV-2 adaptation in cats: A case study of infection in a small household setting
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DOI：
10.1111/tbed.14132
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发表时间：
2021-05-16
影响因子：
4.3
通讯作者：
Dovas, Chrysostomos I.
中科院分区：
文献类型：
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作者：
Chaintoutis, Serafeim C.;Siarkou, Victoria I.;Dovas, Chrysostomos I.
在本研究中，SARS-CoV-2自然感染两只无症状的猫，这是免疫抑制逆转录病毒感染阴性的过程中，进行了调查。这些猫的病毒来源是它们受COVID-19影响的主人，他们在一个小家庭环境中与他们保持接近。主人的体征包括疲劳、打喷嚏、嗅觉丧失和味觉丧失，在症状出现后4天确诊。收集猫的口咽和粪便拭子，以研究SARS-CoV-2 RNA浓度的过程以及病毒传播链的方向性。两只感染猫在不同时间点均为实时RT-PCR阳性。在它们中观察到至少6天的咽部脱落，在第一个采样时间点，即主人临床体征出现后7天，SARS-CoV-2滴度较高（> 7 Log（10）拷贝/拭子）。在一只猫中，在初始下降后，在首次实时RT-PCR阳性拭子后3 - 6天测量到病毒滴度略有增加。该猫的血清学检测显示无血清转化。另一只猫粪便拭子中病毒RNA浓度的变化过程与其咽部中的相似。检测到的SARS-CoV-2毒株，从感染的猫和他们的主人，进行了全基因组测序，揭示了猫的跨物种适应性突变的出现。研究结果支持了人类SARS-CoV-2毒株对猫的适应性相对较好的观点。目前尚不清楚无症状的动物是否会在与未接触过的动物和/或人相互作用的情况下在COVID-19流行病学中发挥作用。我们的研究结果强调了SARS-CoV-2传播给猫的困难，因为无论是两只受感染的猫还是它们的主人都无法将病毒传播给生活在同一个小公寓里的第三只猫，尽管它们在对应于高病毒脱落的日子里非常密切地接触。
In the present study, the course of SARS-CoV-2 natural infection in two asymptomatic cats, which were negative for immunosuppressive retroviral infections, is investigated. The source of the virus for the cats was their COVID-19-affected owner, with whom they were in continuous proximity in a small household setting. The owner's signs included fatigue, sneezing, anosmia and loss of taste, and diagnosis was confirmed 4 days after symptom onset. Oropharyngeal and faecal swabs were collected from the cats, to investigate the course of SARS-CoV-2 RNA concentrations, as well as the directionality of the chain of virus transmission. Both infected cats were real-time RT-PCR-positive on various time-points. Pharyngeal shedding of at least 6 days was observed in them, with high SARS-CoV-2 titres (> 7 Log(10) copies/swab) on the first sampling time-point, that is, 7 days after the onset of owner's clinical signs. In one cat, after the initial decline, slightly increasing virus titres were measured 3 to 6 days after the first real-time RT-PCR-positive swab. Serological testing of this cat revealed absence of seroconversion. The course of viral RNA concentrations in the faecal swabs of the other cat was similar to that in its pharynx. The detected SARS-CoV-2 strains, from both infected cats and their owner, underwent whole-genome sequencing, revealing the absence of emergence of cross-species adaptive mutations in cats. The results support the notion that human SARS-CoV-2 strains are relatively well-adapted to cats. It is still unclear whether asymptomatic animals could play a role in COVID-19 epidemiology, in case of interaction with naive animals and/or people. Our findings highlight difficulties in SARS-CoV-2 transmission to cats, as neither the two infected cats nor their owner was able to transmit the virus to a third cat living in the same small flat, despite their very close contact during the days corresponding to high virus shedding.